Spirometry will be conducted at each post-randomization clinic visit. Six hour post-dose serial spirometry will be conducted at Visits 2, 4, 6, and 8. Trough spirometry will be obtained 23 and 24 hours after the previous day's dose of blinded study medication at Visits 3 to 9. All subjects will be provided with an electronic diary (eDiary) for completion daily in the evening throughout the run-in and treatment periods. Subjects will use the eDiary to record dyspnea scores using the Shortness of Breath with Daily Activities instrument (SOBDA), daily use of supplemental albuterol/salbutamol as either puffs/day from a metered-dose inhaler (MDI) and/or nebules used per day, and any healthcare contacts related to COPD.